ML20010D020
| ML20010D020 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 08/13/1981 |
| From: | Duvall D BBC BROWN BOVERI, INC. (FORMERLY BROWN BOVERI CORP. |
| To: | Stello V NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| IEIN-81-06, IEIN-81-6, NUDOCS 8108210383 | |
| Download: ML20010D020 (1) | |
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Manufacturer of I-T-E Electrical Power Equipment i
August 13, 1981
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I Mr. Victor 9tello, Jr., Director yn
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Office of Inspection & Enforcement
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U. S. Nuclear Reguhtory Commissicn c
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Washington, D. C.
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Dear Mr. Stello:
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The purpose of this letter is to provide a final report on the March 11, 1981 IE Information Notice No. 81-06 entitled " Failure of an ITE Model K-600-4 Circuit Breaker." An interim report on this matter was sent to your office in our letter dated April. 9,1981.
I' The Sacremento Municipal Utility District reported tlnt an ITE Model K-600
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circuit breaker was observed not to trip at its Rancho Seco facility. Their report indicated that a shunt trip device wire slipped out of its wire terminal.
Their report further stated that the shunt trip wire was No. 20, whereas the mating wire terminal was sized for No. 16-14 wire.
It was further reported that the ITE Model K-1600 breakers have the same j
deficiency and that the Model K-3000 breakers may be similarly affected.
Although the K-1600 breakers a e similar to the K-600 breakers, the K-3000 breakers have a different design.
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Three wire terminals (Size 16-14) were returned to us from Rancho Seco.
I These were removed from shunt trip device lead wires.
One of these terminals i
had no wire in the barrel. We assume that this was the one that was reported j.
to have fallen off.
It is apparent by visual observation of this wire terminal, that the reason for it ' separating from the wire was that, it war i
not prorarly crimped.
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'he seccnd sample that was received did have a proper crimp and there was i
evidence that a No. 16 wire was used because there was a small sample left l
in the barrel of che wire terminal.
t A third sample that was received had a proper crimp. However, it waa noted j
by careful removal of the wire that was still remaining in the barrel of the terminal, that this was a No. 18 wire.
I On April 30, 1981, our personnel visited the Rancho Seco facility to further i
evaluate the situation.
It was verifie. that some of the trip coils were j
manufactured with a No. 18 wire and a No. 16-14 knife disconnect wire terminal.
l These crimped connections were inspected and determined to be satisfactory.
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8108210383 810813' gDRADOCK 05000312 f*i'ch'**' 'Y5'**5 Di5i "
i PDR Spring House, PA.9477 * (215) 628-7400
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CBC Brown Beveri Electric, Inc.
BROWN BO/ERI l
Page 2 August 13, 1981 A visual inspection can be made to determine if the crimped connection' is l
strisfactory, If it is, there is no need to replace the wire terminal. We hrne received reports that some personnel performing inspections for this problem have been pulling on wires.
This is not a good practice and could I
cause additional problems.
No. 16 wire has a tensile strength of 50 lbs.
minimum, a No. 18 wire has a tensile strength of 38 lbs. whereas, a No. 20
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wire has a tensile strength of only 19 lbs. As mentioned above, a visual' inspecticin is satisfactory.
Knife disconnect wire terminals are approved for use in circuit breakers to-permit changeout of the shunt trip device without having to splice wires.
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They are not used in svitchgear applications.
It appears that Rancho Seco j;
has replaced the knife disconnect wire terminals with ring tongued terminals 4
which have been bolted together.
This change is not authorized by us for other locations performing inspections.
1, As a res.nlt of IE Information Notice No. 81-06, many utilities have inspected for the reported conditon. Other inspections have been performed by our j
personnel.
None of these inspections has shown any additional conditions similar to that reported at Rancho Seco.
5 The circuit breakers at Rancho Seco were manufactured over ten years ago' and the wire termination on the shunt trip coil lead wire is one of two termina-I tions on the circuit breaker that is made with a hand tool.
All other terminations on the circuit breaker harness are made by machine.
,i From all reports that we have received, we have no reasca to suspect that j
this is a generic problem.
It appears that the incident reported at Rancho l
Seco is an isolated case.
If you need any additional details vith respect to this matter, please feel free to vntact Mr. E. W. Rhoads at 215-628 7660.
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D. DUVALL Vic nt & General Manager Switchgear Systems Division i
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